Re: [PATCH 0/2] -Wuninitialized

From: Ramsay Jones <ramsay@ramsayjones.plus.com>
Date: Mar 20, 2018, 23:02 UTC
Message-ID: <b939f3e7-9ccf-9a26-9ccf-2b2c13853e42@ramsayjones.plus.com>
In-Reply-To: <nycvar.QRO.7.76.6.1803201514490.55@ZVAVAG-6OXH6DA.rhebcr.pbec.zvpebfbsg.pbz>

On 20/03/18 14:46, Johannes Schindelin wrote:

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> Hi Ramsay,
> 
> On Mon, 19 Mar 2018, Ramsay Jones wrote:
> 
>> This series removes all 'self-initialised' variables (ie. <type> var =
>> var;).  This construct has been used to silence gcc
>> '-W[maybe-]uninitialized' warnings in the past [1]. Unfortunately, this
>> construct causes warnings to be issued by MSVC [2], along with clang
>> static analysis complaining about an 'Assigned value is garbage or
>> undefined'. The number of these constructs has dropped over the years
>> (eg. see [3] and [4]), so there are currently only 6 remaining in the
>> current codebase. As demonstrated below, 5 of these no longer cause gcc
>> to issue warnings.
> 
> Thank you so much for working on this!

These patches are based on a very old branch (that goes back at least as far as 2010, see [1]). (I have too many in my repo, so it will be good to remove this one)!

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> In Git for Windows, to work around the MSVC issues you mention, I have
> this ugly work-around (essentially, it has a FAKE_INIT() macro that either
> performs that GCC workaround or initializes the variable to NULL/0):
> 
> 	https://github.com/git-for-windows/git/commit/474155f32a

Oh, wow! (Hmm, actually that doesn't look too bad :-D )

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> FWIW I just tested your patches with Visual Studio 2017 and there are no
> C4700 warnings (the equivalent of GCC's "may be uninitialized" warning)
> [*1*].
> 
> You can find the patches (your patches rebased onto Git for Windows'
> master, plus a patch adding the project files for Visual Studio) here:
> 
> https://github.com/git-for-windows/git/compare/master...dscho:msvc-uninitialized-warning-test

Thanks for testing the patches.

> So here is my ACK, in case you want it ;-)

Thanks!

ATB, Ramsay Jones

[1] https://public-inbox.org/git/4CFA8D4D.2020500@ramsay1.demon.co.uk/